When we mix the streams (zipWith3 (x y z -> x+y+z))
with respect to the chunk structure of the first signal,
computing the first chunk requires full evaluation of all leading chunks of the stream.
However the last value of the third leading chunk
is much later in time than the last value of the first leading chunk.
We like to reduce these dependencies using a different chunk structure,
say

dropMarginRem n m xs
drops at most the first m elements of xs
and ensures that xs still contains n elements.
Additionally returns the number of elements that could not be dropped
due to the margin constraint.
That is dropMarginRem n m xs == (k,ys) implies length xs - m == length ys - k.
Requires length xs >= n.